Dew Point Control for Commercial Applications

Aug 26, 2016

Following questions via a LinkedIn Dehumidification Forum, Munters interviewed Lew Harriman to explain several dew point control related issues and applications, specifically for commercial buildings. To view the interview, please click on the video link to the right.

Lew Harriman is the lead author of The Dehumidification Handbook, ASHRAE Humidity Control Design Guide and the ASHRAE Guide for Buildings in Hot & Humid Climates. Harriman’s 40-year plus experience makes him the expert on identifying the pros and cons regarding RH versus dew point control.

While there are a few commercial applications where dew point control is highly considered such as for supermarkets, ice arenas, and chilled beam/radiant cooling projects, Munters would like to shed light on a better understanding of dew point for comfort applications.

The following diagrams illustrate a Munters dedicated outside air system (DOAS) approach.

What this means:

The purpose of introducing outside air to most commercial buildings is for occupants.

If the building is occupied there will be an internal latent load. That load can, and should be addressed by the DOAS.

That load requires outside air to be delivered at a dew point lower than space design (typical space design is 75°F db, 50% RH, which is 55°F dp), our calculations show the outside air needs to be delivered at 45°F dp based on 200 Btu/hr/person and 15 cfm/person.

Yet, most conventional ERV's do not deliver below space neutral dew point and are not controlled for humidity.

The schedule below shows building exhaust air coming back to the system drier than when it left.

For more information or to reach a local representative, email dhinfo@munters.com or call 1-800-843-5360. To earn PDHs and learn more about dew point control, visit www.munterstraining.com to sign up for the Commercial Applications and Products class.